Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 191450 AAA

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
950 AM CDT Sat Aug 19 2017

Updated for morning discussion.


The JAN 12Z Sat sounding had a PWAT of 1.90in and surface dew
points were running in the mid to upper 70s this morning. Visible
satellite imagery showed very little cloud cover over our CWA
allowing for strong insolation that was helping temperatures warm
through 80s fairly rapidly. Water vapor imagery did show some
drying aloft across northern Mississippi in the wake of a
shortwave dropping over our southern zones which may limit
convection to our southern most zones. Despite the shortwave,
afternoon convection is still expected to be more isolated today
than on Friday and mainly across the southwest half of our CWA.
This should provide little relief though as temperatures climb
into the 90s and combine with the very moist airmass to produce
critical heat index values. The most oppressive conditions are
still expected over the western half of our CWA where a Heat
Advisory remains in effect today. /22/

Prior discussion below:
Today through tonight...Heat stress will be the main concern
through the region today. Anomalously high 925 temps of greater
than 26C will exist in the Lower MS Valley as the mid level ridge
continues to build over the region. Moist surface conditions, due
in part to the amount of rainfall the region has received over the
last few weeks, will make it harder for dewpoints to mix down as
we warm up to the low to mid 90`s this afternoon. Max heat index
values will range from from 103 to 109 degrees with the warmest
values occuring along and west of the MS River. No changes were
needed to the Heat Advisory that will be in effect today to
account for the oppressive conditions. Some locations may find
relief in the form of diurnal thunderstorm activity. The best
chances for these storms will occur in the southern portions of
the ArkLaMiss. Storm chances will diminish after sunset. Lows
tonight will fall into mid 70s.

Sunday through Friday...
At the beginning of the period, mid/upper level ridge will remain
anchored over the area while TUTT continues its westward trek
across the central Gulf of Mexico. While the proximity of the
ridge will yield overall warmer temps in the column, sufficient
low level moisture will still allow for scattered afternoon
convection over the southwest three quarters through Tuesday.
Slimmer convective chances will exist over the northeast quarter
as a wedge of drier low level air remains in this area.

Heat Advisory continuing for Sunday still looks good as mid 90s heat
and mid 70s dewpoints combine for heat indices greater than 105
mostly along and west of I55.

A mid level wave swinging through the OH valley by mid week will
drop a cold front into the area by early Wednesday morning. PWs
above 2 inches will pool ahead of the boundary as it moves south
through the region. This could lead to locally heavy rain with the
associated thunderstorm activity, but the progressive nature of the
boundary may preclude much of that threat.

Much drier air will filter into the region Thursday night into
Friday. Slightly cooler max temps will be felt Thursday and Friday,
but temps Thursday night look to fall into the 60s./26/


12Z TAF discussion:
Mainly VFR conditions are expected throughout the period with the
only exception coming by the way of possible MVFR conditions at a
few sites this morning due to isolated fog cover. Fog will quickly
dissipate after sunrise. Diurnal thunderstorm chances will exist
after 18Z but there was only enough confidence to add VCTS at
KHBG. Winds will remain light through the period.


Jackson       94  75  93  75 /  18  11  21  10
Meridian      93  74  94  74 /  18  11  21   9
Vicksburg     94  74  94  75 /  29  12  20   9
Hattiesburg   94  74  94  75 /  29  11  36  10
Natchez       93  73  92  75 /  36  12  29  10
Greenville    95  75  94  76 /  11  12  18   6
Greenwood     94  74  94  75 /   7  12  22  10


MS...Heat Advisory until 7 PM CDT Sunday for MSZ018-019-025-034>036-

LA...Heat Advisory until 7 PM CDT Sunday for LAZ007>009-015-016-

AR...Heat Advisory until 7 PM CDT Sunday for ARZ074-075.



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